The Steam forums and database was hacked in November, and Valve is still investigating the breach. In a new note to Steam users, Valve head Gabe Newell announced that "it is probable that the intruders obtained a copy of a backup file with information about Steam transactions between 2004 and 2008." The file contained user names and email addresses, and encrypted billing addresses and credit-card information, but it did not include passwords, Newell said.

So far there has been no evidence that credit cards or billing addresses have been compromised from the attack, but Steam users should pay close attention to their accounts and keep Steam Guard on, Newell said. Read Gabe's full update below, which has been sent to all Steam gamers as well.